textproduct: Quad Cities

KEY MESSAGES

- Slightly above average July heat is expected to persist into Saturday with highs in the upper 80s to mid 90s. Heat indices could exceed 100 degrees in some places (50-70% chance) on Wednesday, which is why a Heat Advisory has been issued for portions of northwestern Illinois and far eastern Iowa.

- The breakdown of the ridge on Thursday will lead to increased precipitation chances late week and beyond into next week with a return to more seasonable temperatures.

- Canadian wildfire smoke may potentially impact parts of the region late week and into the weekend as northwesterly flow returns aloft.

SHORT TERM /THROUGH THURSDAY/

Issued at 214 PM CDT Tue Jul 14 2026

The warming trend continues as the near 600-dam 500 mb ridge camps out to our north, keeping subsidence widespread across the area. A surface high pressure over Iowa will limit any type of advection into the CWA, so the air mass is expected to modify each day with highs, lows, and dew points creeping up 1-2 degrees each day through Thursday. Highs today are forecasted to be in the low 90s and inch towards the mid-90s Wednesday and possibly Thursday. Lows are expected to jump from the upper 60s tonight to the low-to-mid-70s by Thursday morning. This will have heat indices teetering on 100 degrees on Wednesday, and a Heat Advisory has been issued for portions of northwestern Illinois and far east-central Iowa where those chances are the highest.

Besides the heat though, there is the potential (40-60% chance) for patchy fog tonight as radiational cooling can maximize with the clear skies. In addition, on Thursday, a weak backdoor cold front across Wisconsin and a lake breeze off Lake Michigan could enhance moisture convergence over northwestern Illinois, west-central Illinois, and far eastern Iowa, spawning some isolated showers and storms (20-30% coverage).

Looking further south, cut-off lobes of positive vorticity are expected to weaken the center axis of the ridge by Thursday. This could split the ridge into two segments: one over the Mountain West and another over the Southeast, setting up the potential for troughing and northwesterly flow to return by the weekend.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Issued at 214 PM CDT Tue Jul 14 2026

Thursday night-Sunday...With the ridge weakening on Thursday, it opens the door for a tropical moisture plume over the Gulf Coast to move northward into our CWA with PWATs likely (60-100%) climbing back above 1.5 inches by Friday morning ahead of the next approaching shortwave on the backside of the longwave trough over the eastern Canada and New England. A developing low pressure system and cold front over the Northern Plains and Minnesota is forecasted to introduce southerly flow near the surface by Friday which could keep the heat around despite the lower heights aloft, but cloud cover and PoPs (30-60%) should prevent heat headlines. By Saturday, the cold front sinks into northern Iowa and Wisconsin, keeping cloud cover and isolated PoPs (10-20%) around, before reaching our CWA on Sunday where the lack of upper-level support should dissolve the front as the next shortwave trough dives into south-central Canada and the Northern Plains.

The northwesterly flow aloft developing late week and through the weekend may also advect Canadian wildfire smoke into portions of the area, per latest RRFS vertical smoke forecasts and smoke forecast from the Canadian Wildland Fire Information System (CWFIS). Trajectories place our region more on the periphery at this time with the greater concentrations and impacts being suggested across Minnesota/Wisconsin/Michigan, but something to keep an eye on.

Monday-Tuesday...An 80+-knot jet streak over the Northern Plains should deepen a low pressure system near the Minnesota- Canada border, forcing another cold front to push into the Central Plains and Midwest. This should boost PoPs and thunderstorm chances on Monday before the front clears the area by Tuesday. In terms of severe weather, it is difficult to speak to the threat level, but the latest LREF guidance is showing a 30-40% chance of at least 500 J/kg of SBCAPE underneath 30+ knots of sfc-to-500 mb bulk shear. Northerly flow at the surface should return for Tuesday behind the cold front, advecting in some much needed cooler air.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 602 PM CDT Tue Jul 14 2026

Much of the TAF period will feature VFR conditions, with mostly clear skies and light/variable winds. Although, tonight between 06-12z, there will be the chance for fog development due to light winds and clear skies, especially in river valleys. There remains some uncertainty on the overall potential and coverage. Thus, opted to hold onto the 4SM and mist at this time, where we will update accordingly as confidence increases. After 12z, we will return to mostly clear skies and light/variable winds. As was mentioned above, there will be wildfire smoke nearby/overhead. Impacts from this near the surface are not expected at this time.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory from noon to 8 PM CDT Wednesday for IAZ042-054. IL...Heat Advisory from noon to 8 PM CDT Wednesday for ILZ001-002- 007. MO...None.